A person responsible wishing to adjust image quality of an image forming apparatus inputs a printing command for a correction pattern to the image forming apparatus. In response thereto, the image forming apparatus prints the correction pattern on paper. The person responsible sets the paper on which the correction pattern is printed and inputs an image reading command to the image forming apparatus. In response thereto, the image forming apparatus reads the correction pattern from the paper and adjusts various parameters based on the results read. As a result, the image forming apparatus adjusts, for example, tone reproduction, or the like.